DINUCLEAR COMPLEXES WITH BRIDGING FUNCTIONALIZED ALKYLIDENE LIGANDS - SYNTHESIS OF THE PHOSPHONIUM [FE2CP2(CO)2(MU-CO)(MU-C(CN)PR3)]SO3CF3 AND OF THE PHOSPHINOALKYLIDENE [FE2CP2(CO)2(MU-CO)(MU-C(CN)PH2)

Replacement of SMe2 by phosphines PR3 (PR3 = PPh3, PMePh2, PMe2Ph, PMe3, P(CH2Ph)3, PPh2CH2PPh2, P(NEt2)3) in the sulfonium [Fe2Cp2(CO)2(mu-CO){mu-C(CN)SMe2}]SO3CF3 (1) results in the formation of the novel phosphonium salts [Fe2Cp2(CO)2(mu-CO){mu-C(CN)PR3}]SO3CF3. The corresponding reaction of 1 with PH3 affords a mixture of [Fe2Cp2(CO)2(mu-CO){mu-C(CN)PH3}]SO3CF3 (3) and the mu-phosphinoalkylidene [Fe2Cp2(CO)2(mu-CO){mu-C(CN)PH2}] (4). Conversion of 3 to 4 is achieved by deprotonating with NEt3 and completely reversed upon treatment with HSO3CF3. The phosphonium and mu-phosphinoalkylidene complexes have been characterized on the basis of their IR, P-31, H-1 and C-13 NMR spectra.